Patents Assigned to McDonald Elevator
  • Patent number: 4449615
    Abstract: A safety brake for hydraulic rams, particularly for hydraulic elevators, includes a plurality of braking members disposed around the piston in a circular array. The outer surfaces of the spaced apart braking members together form the shape of a truncated cone, and the inner surface of a stationary housing surrounding the brake members is complementarily shaped. The angle of inclination of the two conical surfaces is small, and the braking members move downwardly and inwardly only a short distance to engage the piston, so that the conical geometry of the brakes and housing surfaces does not produce significantly mismatched sliding surfaces as the brake members move downwardly.
    Type: Grant
    Filed: August 4, 1981
    Date of Patent: May 22, 1984
    Assignee: McDonald Elevator
    Inventors: Robert W. Beath, John R. McDonald